Extractive distillation and azeotropic distillation are both methods of separating a mixture of liquids into its individual components. However, there are several key differences between the two processes:
Purpose: Extractive distillation is used to separate components that have a large difference in boiling points and are not miscible. Azeotropic distillation is used to separate components that have a constant boiling point and form an azeotrope, a mixture that cannot be separated by simple distillation.
Process: In extractive distillation, a third component called an entrainer is added to the mixture. This component modifies the boiling point of one or more of the components, allowing them to be separated. In azeotropic distillation, the components are separated by a combination of distillation and re-circulation.
Equipment: Extractive distillation requires a column with trays or packing, while azeotropic distillation requires a re-circulation system and a distillation column.
Product purity: Extractive distillation can achieve high levels of purity for the individual components, while azeotropic distillation typically results in a lower purity for the individual components.
In summary, extractive distillation is used to separate components with a large difference in boiling points, while azeotropic distillation is used to separate components with a constant boiling point.